Semiconductor modules are widely used in power conversion devices which are generally used in, for example, hybrid vehicles or electric vehicles. A semiconductor module forming a control device for saving energy includes a power semiconductor element for controlling a large current.
The amount of heat generated from the power semiconductor element tends to increase when a large current is controlled. In particular, with a reduction in the size of the power semiconductor element or an increase in the output from the power semiconductor element, a very large amount of heat is generated from the power semiconductor element. It is very important to cool the semiconductor module including a plurality of power semiconductor elements.
In general, a liquid cooler (hereinafter, also referred to as a “cooler”) has been used in the semiconductor module in order to improve the cooling efficiency of the semiconductor module. In the liquid cooler which circulates a cooling medium, in order to improve cooling efficiency, various methods, such as a method of increasing the flow rate of the cooling medium, a method of forming the heat dissipation fins (cooling bodies) such that a heat transfer coefficient increases, or a method of increasing the thermal conductivity of a material forming the fins, have been conceived.
The cooler is formed integrally with a metal base such that the heat dissipation fins having a thin plate shape are arranged in the flow path of the cooling medium at uniform density, and an insulating substrate on which a semiconductor chip generating heat is provided is bonded to the metal base. Pressure is applied to the flow path to make the cooling medium flow. Then, the exothermic energy of the semiconductor chip is effectively dissipated through the heat dissipation fins with a large surface area by the cooling medium. The cooling medium which is heated by the heat dissipated from the semiconductor chip is cooled by an external heat exchanger, and the cooled cooling medium is compressed by a pump and returns to the flow path in which the heat dissipation fins are arranged.
JP 2001-308246 A discloses a device as the cooler. The structure of the device according to the related art is illustrated in FIGS. 24, 25, and 26.
In the related art, a cooling passage 1002 which is surrounded by a wide cooling passage side wall 1004 is formed in a heat sink 1001. A cooling water inlet 1003a and a cooling water outlet 1003b are formed at the leading end and the rear end of the cooling passage 1002. In addition, openings 1005 are formed in the cooling passage 1002 at positions facing heat dissipation substrates 1104 of two semiconductor modules arranged on the heat sink 1001. A plurality of heat dissipation fins 1105 arranged in parallel on the heat dissipation substrates 1104 is inserted into the openings 1005 and the heat dissipation fins 1105 are immersed in the cooling passage 1002.
A plurality of insulating substrates 1103 is arranged on the heat dissipation substrates 1104 and semiconductor elements 1102 or circuit components are mounted on the insulating substrates 1103. The plurality of insulating substrates 1103 is covered with an upper cover 1101. In addition, a sealing portion 1109 is provided between the heat sink 1001 and the heat dissipation substrate 1104 so as to surround the opening 1005.